Multiple-circuit rheostat and control system



Jan. 21, 1947. H. 1.. RAWLINS ETAL 2,414,556

MULTIPLE CIRCUIT RHEOSTAT AND CONTROL SYSTEM Filed March 20, 1943 3 Sheets-Sheet 1 WITNESSES! Q U jLa M ENJENTORS iczwlins &

1947- H. L. RAWLINS ETAL 2,414,556

MULTIPLE CIRCUIT RHEOSTAT AND CONTROL SYSTEM Filed March 20, 1943 3 Sheets-Sheet 2 fiyz 5 Fr 9. 96' y y I 92 I 2/ 89 23' 90- ear WITNESSES: (P Q INVENTORS 1 Herbert L. Rawlins & M M 77 78 79 21 James M. Wallace.

QU-MQYWQ ATI'OR Y Ian. 21, 1947. wu s ETAL 2,414,556

MULTIPLE CIRCUIT RHEOSTAT AND CONTROL SYSTEM Filed larch 20, 1943 3 Sheets-Sheet 3 WITNESSES: INVENTORS lw-a-l A 4. Herberl L. Rawlz'ns W James M Wallace. Q 7/ I I! I I ATTORN Patented Jan. 21, 1947 MULTIPLE-CIRCUIT RHEOSTAT AND CONTROL SYSTEM Herbert L. Rawlins, Pittsburgh, and James M.

Wallace, Braddock, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa... a corporation of Pennsylvania Application March 20, 1943, Serial No. 479,890

17 Claims.

Our invention relates, generally, to control systems and it has reference, in particular, to multiple circuit rheostats and control systems.

Generally stated, it is an object of our invention to provide a control system for a plurality of circuits which shall be simple and inexpensive to manufacture and easy to operate.

More specifically, it is an object of our invention to provide for gradually increasing and decreasing the energization of a plurality of circuits in succession.

It is also an object of our invention to provide for operatively connecting a control switch to a rheostat to provide for successively connecting the rheostat to one or more of a plurality of different circuits in response to successlve'revolutions of the rheostat contact arm.

Another object of our invention is to provide for periodic or intermittent operation of a switch controlling the connections of a rheostat to a plurality of circuits during successive revolutions of the rheostat arm, and to provide for positively locking the switch except when the rheostat arm is in a predetermined transfer position in each revolution.

Yet another object of our invention is to provide for periodically or intermittently operating switch means in connection with a rheostat so that repeated operations of the rheostat successively increase or decrease the energization of one or more of a plurality of circuits from a. source.

Still another object of our invention is to provide for successively increasing the energization 01- one or more of a plurality of circuits from a source with a given polarity and then, decreasing their energization and repeating the operation with a reverse polarity.

A further object of our invention is to provide a degaussing control system which is simple and eflective as well as easy to operate.

It is also a further object of our invention to provide for operating a switch in connection with rheostat means for gradually increasing and decreasing the energization of a plurality of degaussing circuits with first one polarity and. then the reverse polarity.

Other objects will in part be obvious, and will in part be explained hereinafter.

In accordance with our invention a rheostat of the face plate ty e having a rotatable contact arm and a plurality of stationary contact members connectedat spaced intervals to resistance means is used for radually increasing the energization of one or more of a plurality Of (181 gaussing circuits from a source of direct cur- 2 rent. A switch controlling the connection of the degaussing circuits to the source is operatively connected to the rheostat arm through an interrupted gear train which operates the switch perlodically or intermittently depending on the mode of operation of the arm to successively connect each degaussing circuit to the source, first through the resistance means and then directly, in response to successive revolutions of the arm in one direction. Rotation of the rheostat arm in the reverse direction gradually decreases the energization of the degaussin'g circuits and disconnects them from the source in succession during successive revolutions. Energization and deenergization of the degaussing circuits in the same manner but with the reverse polarity is effected by connecting the rheostat to the source through reversing switch means, and then operating it again in a similar manner.

For a more complete understanding of the nature and scope of our invention reference may be made to the accompanying drawings in which:

Figure 1 is a diagrammatic view of a multiple circuit degaussing control system embodying the principal features of the invention;

Fig. 2 is a front elevational view of a multiple circuit rheostat used in the system of Fig. 1;

Fig. 3 is a side elevational view, broken out in part, of the multiple circuit rheostat shown in Fig. 1;

Fig. 4 is a sectional view of the rheostat face plate taken along the line IV-IV of Fig. 2;

Fig. 5 is a front elevational view of the rheostat shown in Figs. 2, 3 and 4 with the cover and operating handle removed and with the arm approaching the transfer position;

Fig. 6 is a front elevational view of the rheostat similar to Fig. 5 except with the arm past the transfer position and the switch means operated to the next position;

Fig. 7 is a plan view of one of the switch plates of the switch means;

Fig. 8 is a plan view of the other switch plate of the switch means;

Fig. 9 is an enlarged sectional view of one of the auxiliary contact members showing a method 'circuit degaussing control system embodying the rheostat shown in Fig. 10.

Referring to Figure l the reference numeral i9 may denote, generally, a multiple circuit degaussing control system comprising a plurality of degaussing coils or circuits through l4 which are to be connected to a source of direct current by means of the conductors l5 and I6 and a reversing switch i1, so as to be gradually energized therefrom in succession, and then gradually deenergized in succession, connected to the source in the reverse direction and the operation repeated. The gradual energization and deenergization ofthe degaussing circuits may be effected through means such as the rheostat l8 which may embody switch means l9 for controlling its connection to thedifferent circuits. The switch means may be operated by an interrupted gear means 20, whereby the switch means is operatively connected to the rheostat.

Referring to Figs. 1, 3 and 5, it will be seen that the rheostat may comprise a face plate panel 2|, having thereon a plurality of stationary contact members denoted generally by the numeral 22, and arranged for engagement by a contact member 23 mounted on a rotatable contact arm 24. The contact members 25 and 26 of the group 22 may be connectedeto opposite ends of suitable resistance means 21, and the other contact members therebetween connected to the resistance means at spaced intervals. The contact members 28 may be electrically connected to the contact member 26, while the contact members 29 may be dummy contacts not connected to any circuit.

Referring to Figs. 2 and 3 it may be seen that the face plate panel 2| of the rheostat l8 may, be mounted on a frame having vertical support members so with feet 8| at the lower ends for mounting the rheostat on the floor or other substantially horizontal surface. Substantially horizontal support members 32 may be connected to the vertical support members 30 and provided with feet 33 at one end for mounting the rheostat on a wall or other substantially vertical surface and feet 35 at the other end for mounting the face plate panel 2 I.

The resistance means 21 may comprise a plurality of resistance units 38 supported by the vertical frame members 39 and provided with a plurality of taps 39 at spaced intervals, whereby connection may be made to different ones of the contact members 22 of the rheostat by means of conductors 40, which are shown only in part in order to illustrate the construction and arrangement of the rheostat parts more clearly. A suitable housing may be provided for the rheostat comprising, for example, a sheet metal cover 42, perforated sides 43 and a sheet metal front 44, which may be attached to the frame and panel in any suitable manner.

Referring to Figs. 3 and 4 it will be seen that the contactarm 24 may be rotatably supported on the panel 2| by means of a shaft 46 which may either be separate from the arm and attached thereto in a suitable manner, or formed integrally therewith as shown. Means such asthe bearing 48 may be provided for supporting the shaft 46 on the panel. The bearing 48 may. for example, comprise a bushing having a central opening 49 to receive the shaft 46 and a flange 50 which may be secured to the panel by means of bolts 5|. A collar 52 may be secured to the shaft 46 by means of a pin 53 to secure the shaft 46 in the bearing 48. Adjacent the end of the contact arm 24, the resilient contact member 23 may be psitioned in a socket 56 and provided with means such as the Spring for biasing it against the stationary contact members 22.

Operation of the contact arm 24 may be e1- fected in any suitable manner, such as by means of a handle 59 mounted on an arm 60 pivotally connected to the contact arm 24. For example,

5 the arm 60 may be pivotally connected to a channel-shaped support member 6| by means of a transverse pin 62. The support member 6| may be connected to the contact arm 24 by means of bolts 63 and 64 which pass through a block 65 of insulating material secured to the arm 24 by means of bolts 61. The bolt 64 may be sufliciently long so as to provide a support for a spring 68 which is disposed to bias the handle end of the arm 60 away from the face of the cover 44. In order to provide for retaining the rheostat in any given operating condition, means such as the.

plate 19 may be provided on the front 44, having a plurality of circumferentially arranged teeth H on the surface thereof for engaging toothed projections 12 on the adjacent end of the arm 60 when the handle 59 thereof is released.

In order to provide for changing the connections between the degaussing circuits l| through It and the source, the switch means I9 is provided. As shownin Figs. 1, 5 and 6 a plurality of terminals 13 through I9 may be mounted on the panel 2| for effecting connections to the degaussing circuits and the source. The panel 2| may also be provided with a plurality of auxiliary contact members 80 through 85 arcuately disposed with relation to the shaft 46 of the rheostat contact arm 24 and disposed to be connected to the degaussing circuits and the source through the terminal members.

Referring to Fig. 9, which is an enlarged view of the auxiliary contact member 83, it will be seen that the auxiliary contact members may comprise a headed contact portion 86 having an axial stem portion 81 of somewhat reduced section disposed to slide in a bushing 88 mounted in the panel 2|. The bushing 88 may be provided with a reduced opening 89 towards the rear and for receiving a reduced stem portion 99 of the contact member whereby connection may be 45 made to the terminal member and the degaussing circuit M by means ofa conductor 9|. A spring 92 may be positioned within the bushing 88 for biasing the contact portion 86 of the auxiliary contact member outwardly from the face of the 50 panel.

Switch plates 94 and 95, as shown in Figs. 7 and 8, may be mounted on a support 96 of insulating material, as shown in Figs. 1, 4, 5 and 6, and arranged to bridge the auxiliary contact members 55 80 through 85. The insulating support 96 may be rotatably mounted relative to the shaft 46 being, for example, secured to a bushing 91 which may be rotatably mounted on the outer surface of the bearing 48 which is secured to the rheostat panel.

60 The bushing 91 may be provided with a contact arm 98 having a contact member 99 thereon for electrically connecting the rheostat contact arm 29 to one or another of the auxiliary contact members 8| through 83. V

In order to provide for periodically or intermittently operating the switch means l9 so as to move the contact member 99 and the switch plates 94 and 95 from one operating position to another, the interrupted gear means 29 is pro- 7 vided. As shown in Figs. 1, 4, 5 and 6, the insulating support 96 may be provided with a plurality of teeth I09 extending through an arc of substantially 90. Means such as the pinion "ll may be mounted on the panel 2| by means of a bolt I02 for engagement with the teeth I00 of the support plate 96. The pinion may, for example, comprise teeth I03 through I08, the teeth I01, I and I01 having projections I09 on the outer ends thereof.

In order to provide for actuating the switch means I9 to a diflerent operating position in each successive revolution of the rheostat contact arm 24, interrupted gear means IIO comprising teeth III and H2 may be provided on the contact arm 24 for engaging the pinion I M to rotate it through a predetermined distance each time the contact arm 24 completes a revolution.

In order to maintain the switch means I! in a predetermined position during any revolution of the rheostat contact arm, suitable locking means may be provided. For example; referring to Figs. 3, 4. and 6, a ring I I4 may be provided. which interferes with the projections I09 on, alternate teeth of the pinion IOI during any portion of a revolution of the contact arm 24, except when the contact arm is in a predetermined transfer position, and passes over the teeth not having such projections. By providing a slot or recess III in the locking ring H4 in alignment between the toothed projections I I I and I I2 t0v receive the projections I08 oi the teeth I03, I05 and I01 of the pinion IOI, rotation of the pinion IOI may be effected without interference from the locking ring '4 when the contact arm is in the transfer position.

Referring to Figs. 1, 5 and 6, it will be seen that in Fig. 5 the support plate 08 of the switch means II is shown in the initial position as illustrated in Fig. 1, but that the rheostat arm 24 is shown in the position at the completion of its first revolution, moving in the clockwise direction. The toothed projection I I I is engaging the lower tooth I02 or the pinion IOI so that further rotation of the rheostat arm 24 in the clockwise direction operates the pinion IOI in the counterclockwise direction and the support plate 96 in the clockwise direction. Accordingly, tooth I01 moves into the recess between the teeth III and H2 on the arm, and the projection I08 on the tooth I01 is received in the recess II S of the locking plate 4. Further movement 01' the rheostat contact arm 24 in the clockwise direction actuates the pinion III in the counterclockwise direction to carry the tooth I01 past the central line connecting the axes of the pinion I ll and the shaft of the rheostat contact arm to the position at the right as shown in Fig. 6. In this position the locking ring II4 passes in front of or over the now lowermost tooth I08 of the pinion IOI, and prevents further rotation of the pinion by reason of the interi'erence of the projections I00 of the teeth I01,

and I0! in the lower positions on the right and left hand sides of the tooth I04, respectively. The

support plate 08 of the switch means I! is thereby operated so that thecontact member 02 engages the next or the auxiliary contact members 02 in the clockwise direction, and the switch plates 04 and 00 bridge, respectively, the auxiliary contact members 00 and 8|, and 22 through 20. The rheostat contact arm 24 is now free, as shown in Fig. 6, to complete another revolution in the clockwise direction to gradually connect another oi the degaussing circuits tothe source.

Referring to Fig. 1, it will be seen that'the rheostat arm is shown in a position part way through the first revolution in the clockwise direction, during which the energization of the degaussing circuit from the source is gradually increased. The degaussing circuit I4 i shown connected to the source from the conductor I I through the reversbers 19 and 18, and conductor I22 through the re-- versing switch to conductor I6. Continued rotation of the contact arm 24 in the clockwise direction decreases the amount of the resistance means 21 connected in series with the degaussing circuit I4 and conductor I5 of the source, so that when the contact member 23 of the contact arm 24 engages the stationary contact member 28 the degaussing circuit I4 is connected substantially directly to the source through the conductor Ill. Continued movement of the contact arm 24 in the clockwise direction functions as described in connection with Figs. 5 and 6 of the drawings to means 20 through a distance 01' three teeth, thus rotating the support plate 96 of the switch means I 0 through the same distance in the clockwise direction. The contact member 90 is thereby advanced to the auxiliary contact member 82, the switch plate 94 is moved so as to bridge only the auxiliary contact members 80 and BI, and the switch plate 95 is rotated to connect the auxiliary contact member 80 to the source by connecting it electrically to the auxiliary contact members 84 and II. The relative spacing ofthe auxiliary contact members and the contact member 00 and the switch plate 05 is preferably such that the plate 00 engages the contact member 02 before the contact member 09 breaks contact therewith.

When the contact member 23 of the rheostat arm engages the first live stationary contact member 25, the degaussing circuit I2 is initially connected to the source through the resistance means 21. Continued rotation of. the contact arm 24 in the clockwise direction reduces th amount of the resistance means 21 in series with the degaussing circuit I3 and finally it is also connected directly to the source. Successive rotations of 5 the rheostat arm successively connect the degaussing circuits I2 and II to the source in a similar manner. when all or the degaussing circuits have been thus connected to the. source. the direction of so rotation of'the contact arm 24 may be reversed, and deenergization of the degaussing circuits II I2, I2 and I4 may be gradually effected in succession. By operating the reversing switch I1 to the reverse position from that shown in Fig. 1 55 and repeating the operation hereinbefore described, one or more of the degaussing circuits I l through I4 may be radually energized in succession with the reverse polarity, in case the ship or other body with which the degaussing circuits 50 may be associated changes its direction relative to the earth's field, and later deenergized if desired.

Referring to Figs. 10 and 11 the reference numeral III .may denote, generally, a multiple cir- 66 cult commutating rheostat for gradually increasing the energization of one of circuits in succession stwith one polarity and then decreasing their energization and reenergizing them with the reverse polarity with- 70 out requiring the use of an external reversing switch for the circuits. The rheostat II! may be of the face plate type having a plurality of stationary contact members mounted on a panel I It to be connected to suitable resistance means and isposed to be engaged by a rotatable contact rotate the pinion IOI of the interrupted gear.

or more of a plurality relatively small in order arm I25. Switch means, denoted generally by the numeral I23, may be provided for changing the connections of the rheostat to a plurality of load circuits and a source.

While it is possible to use a single set of stationary contact members for connection to the resistance means where the amount of resistance between successive contact members is substantially uniform, this condition is not met in general practice, since the amount of resistance between successive -contact members of a rheostat, which are used when the circuit is being energized at about the maximum current, must be to prevent burning of the contacts, while larger resistance increments may be used adjacent the other end of the rheostat when the current through the circuit is reduced. Accordingly, it is not practical to use the same set of stationary contact members for both directions of operation of a commutating type of rheostat unless two sets of resistance means are used with switch means for alternately connecting them for use. Two sets of stationary contact members I24 and I25 are therefore used. Contact members I21 and I23 may be provided on the contact arm I23, which may be of insulating material, for engaging the sets of stationary contact members I24 and I25, respectively. A single resistance means I29 may be utilized as shown in Fig. 11, comprising, for example, a plurality of resistors such as shown in connection with the rheostat I3 of Fig. 3, and connections to the stationary contact members I24 and I25 may be effected by means of conductors I33 cross-connected between the sets of contact members and the resistance means to provide similarly tapered amounts of resistance between the contact members of the two sets proceeding in opposite directions from their starting points. Contact mem-' bers I3I and I32 of the two sets may be dummy contacts, disconnected from all circuits, to provide for sparkless transfer of the switch means I23, and contact members I33 and I34 may be electrically connected together.

In order to provide for changing the connections of the degaussing circuits I35 through I38, switch means I23 may be provided in operative connection with the rheostat H9. The switch means may, for example, comprise aplurality of arcuately arranged auxiliary contact members. For example, where it is desired to connect 1: different circuits to the source in succession, 2n-I auxiliary contact members may be provided in each of two oppositely positioned groups. The contact members may be connected to the degaussing circuits in pairs, a plurality of opposed spaced pairs of auxiliary contact members I35, I35", I35 and I35, through I31, I31", I31' and I31"" and I38 and I38"being arcuately arranged in opposed relation and disposed to be connected to the opposite terminals of the degaussing circuits I35 through I33, respectively. Additional sets of auxiliary contact members I40 and MI arcuately disposed about the axis of rotation of the rheostat arm I26 in opposed relation, may also be provided for connection to the opposite terminals of a suitable source of direct current.

A support plate I42 of insulating material may be rotatably mounted in a suitable manner and provided with a pair of opposed switch plates I43 and I44 arranged for bridging the concentrically arranged pairs of auxiliary contact members. Suitable contact members I45 and I45 may be provided on the support plate on opposite sides suitable manner, such as of the switch plate I44 for electrically connecting the contact member I21 to the auxiliary contact members I35 through I33", and the contact member I28 to the auxiliary contact members I35" through I38, respectively. Connections between the contact members I and I45 on the support plate and the contact members I21 and I23 on the rheostat, arm may be effected in any by means of conductors to contact members I58 arm I25 and are disposed to engage contact rings I53 and I5I, respectively on the support plate. Connectors I53 and I34 may be provided for connecting the contact rings to the contact members I45 and I43. Suitable means may be provided for electrically connecting the switch plate I44 to the resistance means I23, such as, for example, the flexible shunt I35.

As hereinbefore described in connection with the rheostat I8 of Figs. 1 through 6, interrupted gear means I53 comprising a pinion I51 mounted on the panel H3 and teeth I58 about the periphery of the support plate I42 may be provided as shown in Figs. 10 and 11 for actuating the switch means I23 to different operating positions in response to successive rotations of the rheostat arm I23. The teeth may extend through an arc sufficient to permit the contact member I45 to engage the auxiliary contact members I35 through I38 and the contact member I43 to engage the auxiliary contact members I35" through I33'". Limit switch means I13 and HI may be provided for cooperating with spaced stop means "2,113 for controlling the energizing circuit of a driving motor for operating the rheostat arm I22 between the desired operating limits.

Referring particularly to Fig. 11, the reference numeral I83 may denote, generally, a multiple circuit control system for a plurality of circuits I35 through I33, wherein the rheostat I I3 may be operated by a motor I32 to gradually increase the energization of one or more of the degaussing circuits, and then decrease the energization of the degaussing circuits in succession and increase it I55 and I51 which run and I59 on the rheostat 45 with the opposite polarity.

contact member MI,

The degaussing circuit I35 is connected to the source indicated by the conductors I5 and I3 through the conductor I83, contact member I841) of a suitable switch I34, the left-hand auxiliary contact member I35, conductor I35, conductor I33, degaussing circuit I35, conductor I88, auxiliary contact member I35, switch contact member I45, conductor I55, rheostat arm contact member I21, stationary contact members I24,

stationary contact 200 and 2M through resistance means I23, contact members I34, flexible shunt I55, to switch plate I44, auxiliary contact members I43, and conductor I33 through contact member I84a, back to the source. Rotation of the contact arm I23 in the counterclockwise direction from the position shown decreases the amount of the resistance means I23 connected between the degaussing circuit I35 and the source until the rheostat arm I23 reaches the members I34 which are connected directly to the source through the shunt I35 and switch plate I4I. Continued rotation of the rheostat arm I25 in the clockwise direction results in engagement of the toothed projections with the pinion I51. The pinion is thereby actuated through a distance of substantially three teeth, moving the support plate I42 of the switch means I23 in the counterclockwise direction through a distance of three teeth so that the switch plate I44 moves onto the second switch plate I43, auxiliary the contact member I45 with the degaussing v either manually of the auxiliary contact members I40 which are electrically connected to the source and connects the auxiliary contact member I35 thereto. The degaussing circuit I35 is thereby connected directly to the source.

At the same time the switch plate I43 moves so as to bridge the second pair of auxiliary contact members I and I36"" 01 the lower group, and

of the switch means engages the stationary contact'member I36 which is connected to the upper end of the degaussing circuit I36. Accordingly, the degaussing circuit I36 is connected to the source in series circuit relation with the resistance means I23 in a similar manner to that in which the degaussing circuit I38 was originally connected. Rotation of the rheostat arm I26 in the counterclockwise direction reducesthe amount of resistance in series circuit I36 and then connects source. Successive rotations of the contact arm I26 in the same direction likewise connects the degaussing circuits I31 and I38 to the source. When the switch means reaches its maximum counterclockwise position and the rheostat arm I26 has completed a full revolution thereafter to electrically connect the degaussing circuit I38 to the source, the limit switch means "I and stop means I13 may be disposed to inter,- rupt the energizing circuit for the tor I82.

Reversal of the operating motor may be effected or automatically by means of a reversing, switch 202 to eflect rotation 01' the rheostat arm I26 in the clockwise *dlrection, whereupon the,resistance means I23 is gradually inserted into each of the degaussing circuits I38 through I35 in succession and they are disconnected from thesource. At this point the switch plates I43 and I44 are substantially equidistant between the opposed sets of auxiliary contact members I40 and HI, and the rheostat arm I26 is in the transfer tical, with the toothed projection 200 and 20I already in engagement with and substantially intermediate their transfer operation with the pinion I61.

Continued operation of the rheostat arm I26 in the clockwise direction moves the switch support plate I40 in the same direction, and the contact member I46 of the switch means moves into engagement with the contact member I35' connected to the lower end of the degaussing circuit I35. At the same time the switch plate I43 moves into engagement with the left-hand pair of auxiliary contact members I40 and I35" of the upper group, and the switch plate I44 engages the right-hand auxiliary contact member I. The degaussing circuit I 35 is thereby connected to the source in the reverse sense to that hereinbefore described. For example, the upper end of the degaussing circuit I 35 is connected to the conductor I6 through the conductor I96, auxiliary contact member I40. switch plate I43, auxiliary contact member I35" and conductor 205, while the lower end thereof is connected to the conductor I through conductor I86, auxiliary contact member I35', switch means contact member I46, conductor I51, rheostat arm contact member I28; resistance means I29, shunt I65, switch plate I44, auxiliary contact member- I4I, conductor I63, and contact members I84b to conductor I5. 7

Further rotation of the rheostat arm I26 in the clockwise direction decreases the amount of the resistance means I23 connected in series with it directly with the operating moposition, or substantially ver- I35 until it is finally consource through the contact members I33. Further rotation of the rheostat arm. I26 actuates the switch means I23 to connect the degaussing circuit I35 directly to the source independently of the rheostat arm, and connects the degaussing circuit I36 to the source through stationary contact members I25 and the contact member I28 of the rheostat arm for gradual energization in a similar manner with the same polarity. Successive revolutions of the rheostat arm connect the degaussing circuits I31 and I38 to the source in a similar manner. When the degaussing circuit I38 is connected to the source through the contact member I28 of the rheostat arm, the limit switch means I10 and the stop means I12 are disposed to interrupt the energizing circuit for the operating motor I32. Reverse operation of the motor I82 may be effected either automatically or manually by operation of the reversing switch 202, whereupon the degaussing circuits I38, I31, I36 and I35 are successively deenergized and disconnected from the source.

From the above description and accompanying drawings it will be apparent that we have provided ina simple and effective manner for controlling the energization and deenergizing of a plurality of circuits through the use of a rheostat which may be continuously operated and connected to the different circuits in succession by associated switch means. By providing for periodic or intermittent operation of the switch means in response to movement of the rheostat arm in successive revolutions a simple and inexpensive degaussing control system may be provided. Manual or automatic control of a degaussing system embodying our invention may be readily effected. Since only a single resistance means is required with our arrangement to provide tapered steps of resistance in opposite directions between the corresponding stationary contact members of the different sets of stationary contact members, great savings may be effected by practicing our invention.

Since certain changes may be made in the the degaussing circuit nected directly to the above description and different embodiments oi current and a plurality of circuits, switch means having contact members operable to connect the auxiliarycontact members to the contact arm and to a source of current in difierent predetermined relations in different rotational positions, and means including an interrupted gear train operable to actuate the switch means to a different rotational position for each complete rotation of the contact arm.

2. A rheostat comprising, a rotatable contact arm disposed to engage a plurality of stationary contacts arranged substantially in a circle and connected to resistance means at spaced intervals, a plurality of terminals for effecting connections to a plurality of external circuits and a source of current. a, plurality of auxiliary contacts connected to the terminals, switch means including a rotatable switch plate for connecting the auxiliary contacts in different predetermined relations in different rotational positions, and interrupted gear means operated in response to movement of the contact arm to actuate the switch plate to a different rotational position at the termination of each rotation of the contact arm and change the connections of at least one of the external circuit terminals with one of the source terminals.

' 3. A multiple circuit rheostat comprising, a rotatable contact arm disposed to engage a plurality of stationary contacts connected to resistance means at spaced intervals, circuit means including a plurality of auxiliary contacts and switch means positionable to difierent positions to progressively connect the auxiliary contacts to a source of current first through the resistance and then directly, and interrupted gear means operatively connecting the switch means to the contact arm when the arm is in a .predetermined position for moving the switch means to a diiiferent operating position in response to movement of the contact arm.

4, A rheostat comprising, a rotatable contact farm disposed to engage a plurality of contact ,menibers connected to resistance means at spaced "intervals, a plurality of auxiliary contact membars for 'efi'ecting connections to a plurality of "external circuits, movable switch means successively connecting the auxiliary contact members to the contact arm and to a source of current, and means operable in response to movement of the contact arm adjacent the termination of successive rotations thereof to move the switch means periodically to transfer the connection of one of the auxiliary contact members to the source and connect an adjacent auxiliary contactmemher to the contact arm.

-5. A multiple circuit rheostat comprising, a rotatable contact arm disposed to engage a plurality of stationary contact members connected to resistance means at spaced intervals, a plurality of resiliently mounted auxiliary contact members,

and switch means intermittently operable in response to successive rotations of the contact arm to successively connect adjacent auxiliary contact members to the contact arm and to one end of the resistance means.

6. The combination with a rheostat having a rotatable contact arm disposed to engage a plurality of stationary contact members connected to resistance means at spaced intervals, of a plurality of arcuately arranged auxiliary contact members, switch means including a rotatable switch member operable to different positions to connect the contact arm to diflerent of the auxiliary contact members and movable contact means bridging the others of the auxiliary contact members, and means operatively connecting the. switch means and the contact arm when the contact arm is in a predetermined position during each revolution, said means actuating the switch means, each revolution to connect a different auxiliary contact member to the contact arm and bridge the others of the auxiliary contact members.

'7. The combination with a rheostat having'a rotatable contact arm, of a plurality of auxiliary contact members, switch means including a movable contact member electrically connected to the arm and movable relative thereto disposed to engage different of the auxiliary contactmembers in difierent positions and a bridg ng member arranged to bridge th auxiliary contact members on one side of the arm, and interrupted gear means operable in response to rotation of the contact arm through a predetermined zone in each revolution to actuate the switch means to move the arm to an adjacent auxiliary contact member.

8. A degaussing control system for a plurality of degausssing coils disposed to be successively gradually energized and deenergized for demagnetizing a magnetic body comprising, circuit means connecting one end of each of the coils to one side of a current source, a potentiometer rheostat having resistance means connected across the source and a rotatable contact arm disposed to make an adjustable connection to the resistance means at difierent points, switch means positionable to connect the other end of each coil to the contact arm and to the other side of the source in predetermined order for a given direction of rotation of the switch means, and interrupted gear means operatively connecting the switch means and the contact arm periodically for positioning the switch means in different positions in response to predetermined movement of the contact arm in each revolution.

9. A multiple circuit rheostat comprising, a rotatable contact arm having a pair of contact members. insulated from each other and disposed to engage difierent sets of stationary contacts cross-connected in opposite senses to spaced points on a common resistance means, a plurality of pairs of oppositely positioned auxiliary contact members, and switch means includin movable switch members operable periodically in response to rotation of the contact arm to suecessively connect difierent of the auxiliary contact members to the contact members of the contact arm and to a source of electrical energy.

10. A multiple circuit rheostat comprising, a rotatable contact arm having a pair of movable contact members for engaging different sets of stationary contact members connected at spaced intervals to resistance means, a plurality of pairs of auxiliary contact members arranged in op posed relation for connectioi to the opposite terminals of a plurality ofcirc iits to be gradually energized and deenergized in opposite senses, and switch means including movable switch contact 60 members positionable in different positions to connect different of the auxiliary contact members to the movable contact members of the contact arm and to a source of electrical energy. 11. A control system for n degaussing circuits 55 to be successively gradually energized and deenergized with one polarity and then gradually energized and deenergized with the reverse polarity comprising, rheostat means having a rotatable contact arm with a pair of radially spaced conco tact members insulated from each other for engaging concentrically arranged sets of stationary contact members connected to a common resistance means at spaced intervals in opposed relation, oppositely positioned sets of 2n--l aux- 65 lliary contact members arcuately arranged substantially concentrically with the stationary contact members of the rheostat means, circuit means connecting opposite ends of the nth degaussing circuit to the intermediate auxiliary 70 contact members of the oppositely positioned sets and successive pairs of auxiliary contact members on each side oi the intermediate contact members to the n-ith, n--2th and 1st degaussing circuits respectively, additional auxiliary contact means associated with each set of auxiliary contact members one of said contact'means being connected to the positive terminal of a source electrical energy and the other to the negative terminal, switch means including an insulating support having oppositely positioned switch plates forconnecting the auxiliary contact members to theadditional contact mem bers and to the opposite ends of the pair of concentrically arranged rheostat contact members and a pair of switch contact members positioned intermediate the switch plates connected to the contact arm contact members and arranged to engage the auxiliary contact members of the different circuits, and means including interrupted gear means operatively connecting the switch plate and the contact arm at a predetermined point in each revolution of the contact arm to abruptly rotate the switch means for connecting one of the switch contact members to the next auxiliary contact member, whereby the contact arm may be connected to successive degaussing coils during successive revolutions for progressively energizing them in turn and then proaressively deenergizing them.

12. A deguassing system comprising, a plurality of degaussing circuits disposed to be gradually energized and deenergized for neutralizing the magnetic field induced in a magnetic body by the earth's magnetic field, a potentiometer connected across a source of direct current and having a rotatable contact arm, switch means operable successively to connect different ones of the circuits to the source through the contact arm and the potentiometer and then directly to the source, and means operatively connecting the contact arm and the switch plate to connect the different circuits to the contact arm and to the source in predetermined sequence in response to successive revolutions of the contact arm.

13. A rheostat comprising, a plurality of fixed contact members connected to resistance means at spaced intervals and disposed for engagement by a rotatable contact arm, a plurality of spring biased contact members arcuately disposed about the axis of rotation of the arm, switch means including a plate having contact means to engage the spring biased contact members, gear means operable to actuate the switch means, means operativeiy connecting the contact arm to the gear means periodically to actuate the switch means in each revolution of the arm, and means lock-' ing the gear means during the remainder of each revolution.

14. A rheostat comprising, a rotatable arm for engaging a plurality of fixed contact members mounted on a support, a plurality of resilient stationary contact members mounted on the support, switch means operable to engage the resilient contact members, interrupted gear means including a pinion operatively connecting the arm and the switch means to change the connections of the switch means and the resilient contact members periodically in each revolution of the contact arm, said pinion being provided with an even number of teeth and alternate of the teeth having proiections on the ends thereof, and a rotatable guard ring provided with a recess for receiving one of said projections in a predetermined position of the ring, said ring being actuated in response to rotation of the contact arm to mechanicallyinterlock with others of the projections of the gear means to prevent further movement of the switch means during a rotation of the contact arm. i

15.- A control system for a plurality of dogs-ussingwindings disposed to be graduallyenergized iroma direct currentnsource with-a given-polarity and deenergized, and then 'energized gradually with the reverse polarity and deenergized comprising, resistance meansv cross connectedbetween a pair ofconcentrically arranged sets'of fixed contact members in opposite senses, a rotatable contact arm having a pair of contact members for engaging said sets of fixed contact members, a plurality of arcuately arranged sets resilient contact members positioned in spaced pairs in opposed relation and connected to the opposite ends of the degaussing windings and to the source, switch means operable to connect the resilient contact members to each otherand to the contact members on the contact arm, interrupted gear means operable periodically in response to rotation of the contact arm to move the switch means the distance between adjacent resilient contact members in each revolution of the arm, driving means for the contact arm, and limit switch means operable to stop the driving means when the switch means reaches a predetermined position.

16. A multiple circuit commutating rheostat comprising, resistance means, a plurality of stationary contact members arranged in substantially concentric circles for engagement by spaced contact members on a rotatable rheostat arm, circuit means connecting the resistance means at progressively diiferlng spaced intervals t the concentric sets of contact members in opposite senses,'a plurality of spaced pairs of auxiliary contact members arranged for connection to opposite terminals of a plurality of circuits to be energized and deenergized in opposite senses, an additional plurality of auxiliary contact members disposed in opposed groups in conjunction with said auxiliary contact members and disposed to be connected to the opposite terminals of a current source, means including contact means operable to connect said additional auxiliary contact members to the adjacent auxiliary contact members to effect energlzatlon thereof with opposed polarities, and contact means selectively operable depending on the position of the switch means to connect the auxiliary contact members of the set opposite to that engaged by the afore- 50 said contact means to the other terminal of the source through one or another of the rheostat arm contact members,

17. A multiple circuit commutating rheostat for a plurality of circuits comprising, a common 55 resistance means, a pair of concentrically arranged sets of stationary contact members disposed ior engagement by spaced contact means on a rotatable arm, circuit means connecting the vim sets of stationary contact members to the rec sistance means at different spaced intervals in opposed senses, oppositely positioned sets of auxillary contact members disposed to be connected to opposite terminals of the plurality of circuits, switch means including a rotatable support having contact means for connecting one of the sets of auxiliary contact members to one of the contact means of the arm and switch plates for connect-' ing the other of the sets of auxiliary contact members to one terminal of a direct current source and the resistance means to the other terminal thereof when the switch means is rotated through a predetermined angle of operation, additional contact means associated with the switch means for connecting the other of the sets of auxiliary contact members to the other of the contact means of the arm when the switch means is rotated through another predetermined angle of operation, said switch plates being operable to connect said one set of auxiliary contact members to the other terminal of the direct current source and the resistance means to said one terminal thereof, and interrupted gear means pperatively connecting the switch means to the rheostat periodically in each revolution for rotating the switch means with the arm to connect another of the circuits to the source through the resistance means.

HERBERT L. RAWLINS. JAMES M. WALLACE. 

